1. Field of the Invention
This invention relates to valve devices for controlling a flow stream. More specifically, this invention relates to valves with ceramic plug and a ceramic seat, suitable for control of hot, erosive flow streams.
2. Description of Related Art
A variety of valve devices have been used for some time in the control of fluid through a conduit. Typically, these prior devices are either made of non-ceramic materials that tend to wear away quickly in hot, erosive flow streams or, if having a ceramic plug and seat, generally do not permit the ceramic plug and ceramic seat to come in physical contact in order to avoid contact failure, however such prior ceramic plugs and seats are typically unable to entirely shut off the flow, but can only throttle down the flow by narrowing the gap between the plug and the seat.
It is desirable to provide a valve with a ceramic plug and a ceramic seat that can shut off the flow through the valve entirely, and that is suitable for controlling the flow of hot, erosive flow streams.
Therefore, it is the general object of this invention to provide a valve device that has ceramic plug and seat components and which is able to shut off the valve entirely.
It is a further object of this invention to provide a valve that has an inner plug head, which modulates and the throttles the amount of flow passing through the valve when the valve is open.
It is another object of this invention to provide a valve that has an inner plug head that is shaped in such a manner so that as the valve plug approaches the closed position, the inner plug head blocks most of the flow path, thereby reducing the flow to a small amount.
Another object of this invention is to provide a valve that has an outer plug head that contacts the valve""s outer ceramic seat as the valve reaches the closed position.
A further object of this invention is to provide a valve that entirely shuts off flow through the valve as the outer ceramic seat contacts the outer ceramic plug.
These and other objects of this invention are achieved by the device described herein and are readily apparent to those of ordinary skill in the art upon review of this disclosure and/or ordinary experimentation with the device described herein.